CALIFORNIA (KRON) – A Mountain View High School teacher has been placed on paid administrative leave after comparing President-elect Donald Trump to Adolf Hitler during a history lesson.

Frank Navarro has taught at the school for almost 40 years.

Navarro was placed on leave Thursday after a parent wrote an email to administrators about comments he made in class.

School officials confirmed this Saturday to KRON4 News. They did not say what the parent said in the email and did not tell Navarro either.

Navarro is an expert when it comes to the Holocaust.

School officials also refused to review his lesson plan with him.

A Change.Org petition has been started asking Mountain View High School Principal David Grissom to reverse Navarro’s administrative leave.

“I feel strongly about this: to stand quiet in the face of bigotry and to turn your eyes away from it is to back up the bigotry, and that’s not what I, or any history teacher, should be doing in our work,” Navarro said.